In March 1943, the cryptanalysts at Bletchley Park, Britain's code-breaking centre, are facing their worst nightmare: Nazi U-boats have
unexpectedly changeed their Enigma cipher and a merchant shipping convoy with 10,000 people on board is in peril. The authorities turn for help
to Tom Jericho (Scott), a brilliant young mathematician and code-breaker. Unknown to his colleagues, Jericho also has another equally bafflling
enigma of his own to unravel: Claire (Burrows), the woman he loves, has disappeared and he suspects there may be a spy in Bletchley. To get to
the bottom of both mysteries, he enlists the help of Hester (Winslet), Claire's best friend and co-worker at Bletchley. Together, they keep
one step ahead of secret services agent Wigram (Northam), to reach a conclusion that uncovers both international and personal betrayals.
Based on the novel by Robert Harris.